The present invention relates to an electrophotographic photoconductor. More specifically, the present invention relates to an electrophotographic photoconductor for use in a laser printer or a plain paper copier. Even more specifically, the present invention relates to an electrophotographic selenium photoconductor (more simply referred to as a "photoconductor") comprising a photosensitive film formed by vacuum-depositing a selenium-arsenic alloy onto a conductive substrate.
Selenium photoconductors, often used as electrophotographic photoconductors, are manufactured by vacuum-depositing a selenium film onto an outer surface of a conductive substrate of an aluminum alloy. In, for example, laser printers or plain paper copiers, the outer surface of the conductive substrate is cylindrical in shape. Selenium-arsenic photoconductors, also formed by vacuum-depositing a selenium-arsenic alloy onto a conductive substrate, are used predominantly as a single-layered photosensitive film.
When mounted in, for example, a large-scale, high-speed printer capable of printing about 40 to 150 A-4-sized sheets per minute, a conventional single-layered selenium-arsenic photoconductor provides sufficient photo response. However, with printers capable of printing 300 or more sheets per minute, the single-layered film structure provides insufficient photo response due to small light exposure impinging on the surface of the photoconductor. This insufficient exposure deteriorates image quality when printing at such high speeds.
In addition, due to large variations in sensitivity depending on the wavelength of the light source, the single-layered selenium photoconductor does not enable free selection of the wavelength of the light source for a printer using the single-layered selenium photoconductor. Therefore, the conventional photoconductor-mounting machine is usually responsible for reducing the variation of the wavelength of the light source.